Nitrogen Form Part Of The Growth Of Rice Under Physiological Indicators Of Water Stress

The developments of economy, society, science and technology of most countries in the world have been threatened seriously by the shortage of water resource these days. Our country has been troubled with the same problems. Limited water resource has become one of the main restrictive factors to sustainable agriculture. Traditional water-logged cultivation of rice consumed a huge amount of water and led to some serious environmental problems especially when large dosage of fertilizer and pesticide had been applied. Water saving agriculture has evidently become the correct direction of the sustainable agriculture. As rice has the adaptation to both water-lodged and aerobic condition, the new kind of water saving mechanism, aerobic cultivation of rice is gaining more and more attention from scientists, government and farmers. A series of imitating experiments in lab were carried out to study the responses of different cultivars of rice to aerobic cultivation, the N nutrition characteristics of rice in simulation water stress condition, and the effects of depth of groundwater on growth and rice yield, (1) Effects of water stress on germination of rice, (2) the effects of water stress and different nitrogen nutrition on soluble substance content of rice, (3) the effects of water stress and different forms of nitrogen nutrition on the growth of rice and nutrient acquisition.The main results are as follows.Rice germ is more sensitive to water stress than ridicule under water stress. Suitable water stress can promote the growth of ridicule, and repress the growth of germ. Under 50g·L-1PEG water stress, water containing in rice seed rises. And the concentration of K+,soluble suger,sucrose,proline in rice seed is greatly improved. The activity of SOD,POD and CAT in Shanyou 63, stronger anti-drought, goes higher.Under water stress and none water stress conditions, soluble substance concentration of rice stem, leaf and root is the lowest in the time of equal amounts of NH₄⁺-N and NO₃^--N. The other two treatments under water stress is higher than under normal water condition except for equal amounts of NH₄⁺-N and NO₃^--N. Under the two water conditions, sucrose content of rice stem, leaf and root system increases when the rate of NH₄⁺-N and NO₃^--N is rise. Under water stress is lower than under normal water condition except for equal amounts of NH₄⁺-N and NO₃^--N.Soluble substance concentration of bleeding sap of rice treated with the nitrogen by 1/9 of NH₄⁺-N to NO₃^--N was the highest under normal water condition. And it reduced with the ratio of NH₄⁺-N to NO₃^--N increase. Under water stress condition, sucrose concentration of rice bleeding sap increased with the ratio of NH₄⁺-N to NO₃^--N increase.Under normal water condition, high ratio of NH₄⁺-N supplication was advantageous in dry matter accumulation in rice shoots and increased plant height; high ratio of NO₃^--N promoted dry matter accumulation in rice roots and increased root length. Under water stress condition, equal amounts of NH₄⁺-N and NO₃^--N supplication promoted the growth of shoot. Under both of water stress and none water stress condition, high ratio of NO₃^--N supplication increased total root length, surface area and volume. Under normal water condition, total absorption area of root increased with the rate of NO₃^--N increase. Equal amounts of NH₄⁺-N and NO₃^--N reduced the influence of water stress on rice water absorption.